For terrestrial or astronomical use, this diagonal produces a right-side-up, non-reversed image with correct daytime orientation
Fully coated prisms for superior image fidelity and maximum light throughput
Accepts 1.25" eyepieces, fits in 1.25" focusers
Not recommended for use in Newtonian reflector or Dobsonian reflector telescopes
Requires 5/8" more focus travel than typical star diagonals
For terrestrial viewing with a refractor or Cassegrain telescope, use of a correct-image (or image erecting) prism diagonal may be desirable. The image through the eyepiece image will appear upright and non-reversed, matching the naked-eye orientation. So a correct-image diagonal is essential for terrestrial viewing with the above telescope types and is useful for astronomical viewing for those that prefer to have the view through the telescope match the naked-eye orientation. Note that the 45-deg correct-image diagonal requires 5/8" more focus travel than typical diagonals. Diagonals are not recommended for use in reflector telescopes.